993 Carrera central locking problems, idle loping problems

SCCA-racer03 · 04-20-2008, 07:54 AM

Hi guys I'm working on a 95' 993 for a friend of mine. Manual tranny with 58k miles. Two problems I'm trying to fix are:

The central locking system only works and arms the alarm system when you manually use the key. If you try to use the remote, it will make the little horn beep like it is locked, and you will here a locking sound (only on the passengers side) but all doors will remain unlocked. The LED lights on the doors will not flash. The remote also immobilizes and mobilizes the ignition as it should. Just the doors wont lock and the alarm won't arm. It works fine if you use the key. I'm going to change the batteries in the remote though I highly doubt that will help. Could the receiver be bad?

Second problem is that when the car starts up cold, the ignition lopes from about 900rpm to 500 rpm constantly. I have pulled the IAC valve and cleaned it to no avail.

Don Plumley · Don Plumley's Garage

For central locking I'm guessing you have a fuse or relay problem.

For the cold rough idle, the possibilities range from the ICV (which you cleaned), O2 sensor, dirty MAF, flywheel sensor, knock sensor and vacuum leak. It's not likely a failing DMF as it's a cold idle problem. Easiest is to clean the MAF with some CRC MAF sensor spray. Does it have a cone filter or K&N oil filter? How old is the O2 sensor?

Search here for information on how to read the CEL codes without a scanner (unique to 95's).

SCCA-racer03 · 04-20-2008, 08:50 AM

I'll clean the MAF and see. It does not have a CEL on right now. The car is bone stock with a paper filter element.

Last service the car had was its 30k major service at 45k miles. Its about that time for the 60k major service.

Could it have a code stored without the CEL on? I'll do a search.

I'll check the fuses too.

Don Plumley · Don Plumley's Garage

Yes, I believe it can store a code without triggering the light.

Check the distributor caps, rotors, and also the distributor belt. To check the belt I typically rotate the engine and watch the rotors turn. You can also disconnect the coils one by one.

SCCA-racer03 · 04-20-2008, 06:00 PM

Ok, so no fuses out, still stumped on why the locking system is not working with the remote fob, but the engine immobilizer is.

I cleaned the MAF, the MAF housing c-clamp had fallen off so it was just kind of hanging loose on the rubber intake boot. That sure wasn't helping.

Also found this vacuum connector leading no where. I'm sure it is supposed to lead somewhere, any ideas? Couldn't find any other loose stuff.

Seems to be running better now, but for whatever reason it only lopes when the air temp gets down below 50 degrees or so. I'll try it in the morning and see if its still doing it.